The U.S. Pat. No. 4,516,495 teaches a method of positioning in a printing location a second pattern, deriving from a first pattern formed on a stencil, in relation to print material intended to receive the second pattern, and in which method the second pattern is formed by causing a coating substance or an ink paste to pass through perforations or open meshes in the cloth forming the first pattern and onto the print material, e.g. with the aid of a squeegee arrangement in a silk screen printer.
According to this known method the two-dimensional position of the second pattern in relation to a reference point, normally a frame part of the printer, is stored in a memory, and when the material to which the second pattern is transferred has been moved to a printing position, the prevailing position of the material or the prevailing position of a pattern applied to the material is evaluated together with any discrepancy which would occur if the second pattern were to be applied to the print material while the material occupied its present position.
It is also proposed that a frame carrying a stencil exhibiting the first pattern and/or a printing table and/or the actual printing material is displaced in response to the magnitude and directional sense of the discrepancy to an extent such that when the second pattern is applied to the print material in this printing position, the pattern will have a position on the material in which the previously identified discrepancy is fully compensated for or satisfactorily compensated for.
The proposed method requires one or more material-positioning detecting and establishing devices to be introduced between stencil and print material when the material occupies a printing position, so as to enable the magnitude and directional sense of the discrepancy to be evaluated, and further requires the print material or the pattern to be displaced in order to compensate for the evaluated discrepancy prior to commencing the printing operation.
The disclosures made in U.S. Pat. No. 4,221,165 also form part of the prior art, this specification teaching a silk screen printer which includes a plurality of gripping beams which, in a first position--a material feed position, grip the material on which print is to be applied in a second position, a printing position, while registering the gripping beams.
This enables the print material to be moved along a precise transport path from the material feed position to the printing position. This precise transport path is afforded by the fact that each of the gripping beams can be registered relative to the printer chassis, or a part thereof, both of said positions.
For the purpose of registering the print material in the first position, it is proposed that in addition to a first registering means co-acting with the gripping beams a separate means is provided for co-action with the print material, so as to obtain precise registration of the print material in the first position, such that a registered gripping beam is able to collect a pre-registered print material and transport said material through an exact distance to the printing position.